IMMUNOPHENOTYPING OF HUMAN HT29 COLON-CANCER CELL PRIMARY TUMORS AND THEIR METASTASES IN SEVERE COMBINED IMMUNODEFICIENT MICE

The immunophenotype of HT29 human colon cancer cells implanted into se vere combined immunodeficient mice was assessed in primary rumours and their metastases in the lungs using an indirect immunohistochemical m ethod. After primary tumours were surgically removed, the metastases w ere given time to develop, thus paralleling the clinical situation. Wh ile vimentin was negative in both primary and secondary rumours, E-cad herin was present as membrane-bound labelling in the primary rumours o nly. Whereas the markers p53, MIB1, PCNA and CEA were consistently pos itive in both primary and metastatic rumours, CD44 variant 6 and CA125 were negative in metastases but positive in the primary rumours. Ther e was a significant increase in the percentage of cells labelled for p 53 in the primary rumours compared with the metastases. For the prolif eration markers, there was no significant difference in labelling betw een primary tumours and metastases for MIB1. Of the cytokeratins exami ned, CK 20 gave the strongest and most consistent reaction in both pri mary and secondary tumours. The results indicate that, for certain imm unohistochemical markers, results are the same in both primary tumours and metastases. Hence, in these cases, antigens that are expressed on the primary tumour as well as on the metastases can serve as target m olecules for immunologically based forms of treatment of metastases.